Type 21 Frigate

TYPE 21 1

There was a time when Britain’s shipyards provided the world’s navies with the finest warships. British designs were highly sought after particularly in South America, Africa and Australia but in the 1960s this export success took a dramatic turn and the United States became the primary supplier of warships to the western world. British shipbuilders thought they knew exactly who to blame; the Royal Navy itself. The fact of the matter was that British warship designs were first and foremost tailored to British requirements and then modified to suit an export customer. In the 1960s the increasingly leaner Royal Navy opted for more sophisticated vessels to make up for the smaller number of hulls in service. The result was a number of ships that were exceptionally high in quality but subsequently came with an extremely high price tag.

British shipbuilders felt that under these conditions the chances of achieving export success with the newest designs was becoming less and less likely. They therefore lobbied the Royal Navy and Parliament to produce the next class of RN frigate free from any government specification. They argued that they could produce an effective warship ideal for the convoy protection role that would be cheaper than contemporary warships such as the superlative Leander-class. In a rather bold move the Admiralty were wooed in to agreeing.

TYPE 21 2

The result was the Type 21 frigate, known as the Amazon-class, and in trying to achieve the goals promised by the shipbuilders the type failed appallingly. First-of-class HMS Amazon was completed in 1974 at a cost of no less than a Leander-class and sea trials proved that despite her relatively small size she was overweight compared to the original proposal. Stability problems with the ship being top heavy would dog the class throughout their entire service life and often this resulted in ballast tanks being filled to counteract this problem. RN planners began to realize that with this top heavy problem the class would prove difficult-to-impossible to modernise with the new sensors and weapons then in development as this would upset this balance further.

Crews initially complained of the vessel being quite overcrowded in places despite a high degree of automation for the time. Although smaller than a Leander-class the crew complement was similar but this criticism died away when they saw how luxurious (at least compared to previous warships) the crew compartments were. It was one of the first ships in the Royal Navy to properly take in to consideration ergonomics and crew comfort leading many to consider the ship the cushiest job in the fleet. The work stations were very modern and made crews transferring from older ships feel like their new vessel was a quantum leap in performance even if it wasn’t entirely true.

TYPE 21 3

The Type 21 was propelled by a twin shaft arrangement with propulsion provided by an all-gas turbine configuration. The primary powerplant comprised of two Rolls-Royce Olympus engines, a maritime development of the same aviation engine that powered aircraft such as the Avro Vulcan and most famously the Aerospatiale/B.A.C. Concorde. These produced over 50,000shp and were used for propelling the ship to its top speed of 30knots. The smaller secondary Rolls-Royce Tyne gas turbines provided secondary power and could be used for cruising while diesel generators produced electricity for the onboard systems. When operating at an economical cruise speed of 17knots the Type 21 had an operating range of around 4,000 nautical miles.

HMS Amazon and HMS Antelope were completed with a weapon fit comprising of a single 4.5inch dual purpose gun, a weapon that had proven highly successful on the Leander-class once problems with stoppage had been resolved, and had both anti-ship and limited anti-air capabilities with target data provided by radar although final training of the weapon was done manually. Dedicated anti-air weapons consisted of a Sea Cat surface-to-air missile (SAM) launcher and two 20mm Oerlikon anti-aircraft guns. Against large maritime patrol aircraft like the Soviet Il-38 “May” it would be reasonably effective but against a fast jet however it was almost useless. It also had a useful secondary role as a weapon against fast attack craft like the Soviet Osa-class torpedo boat and there was also the capability to use it to attack a target on the shore such as an artillery gun emplacement.

As the first two vessels were being built however there were already concerns that the type would be poorly matched against the increasing threat from the rapidly modernizing Soviet Navy surface force. Therefore from the third ship onwards a minor redesign allowed the following vessels to carry MM38 Exocet anti-ship missiles. The missiles were mounted on a platform ahead of the bridge and this necessitated the relocation of the decoy deployment system further aft as this had been where it had been located in the early ships. This dramatically improved its ability to engage hostile ships out to a range of 28 miles and thsi feature was retrofitted to the earlier ships later.

TYPE 21 4

Initially the Type 21 had no indigenous anti-submarine warfare (ASW) capability in the form of torpedo tubes or the Ikara ASW missile as equipped other RN warships but instead relied entirely on its helicopter. At first the Westland Wasp was the only RN helicopter small enough to operate from the flight deck but it was always intended to carry the new Westland Lynx which was replacing the Wasp from the late 1970s. The Lynx was a formidable ASW weapon being capable of independent detection and attack as well as insert Royal Marines on to another ship or beachhead. It also had a potent anti-fast attack role when fitted with a quartet of Sea Skua missiles. The Type 21 could only operate a single aircraft and the problem with this arrangement was that if the aircraft was shot down or became unserviceable on the flight deck due to mechanical breakdown then the frigate was effectively defenceless against hostile submarines and would have to rely on support vessels for protection. This fact was not lost on the Royal Navy who again modified the ship with two triple mounts for launching Mark 44 or 46 torpedoes.

The eighth and last ship was completed in 1978 and the class asserted itself within the Royal Navy operating primarily in the North Atlantic. The class consisted of;

  • HMS Amazon (F169)
  • HMS Antelope (F170)
  • HMS Active (F171)
  • HMS Ambuscade (F172)
  • HMS Arrow (F173)
  • HMS Alacrity (F174)
  • HMS Ardent (F184)
  • HMS Avenger (F185)

Despite the early misgivings, the Admiralty seemed happy with their newest ship. It was an aesthetically pleasing design looking modern and clean compared to previous classes and despite being heavier than had been intended the powerful propulsion system afforded the vessel a high degree of manoeuvrability. Some of the more practical naval officers still recognised the class’ shortcomings however and when the Falklands War broke out in 1982 these officers were naturally concerned. Seven of the eight ships of the class were made available for the conflict with HMS Amazon away in the Persian Gulf at the time.

TYPE 21 6

The Type 21s formed part of the 4th Frigate Squadron and were initially tasked with escort duties for the taskforce’s larger ships such as the carriers, supply ships and the troopships. HMS Arrow had the distinction of being the first British warship to fire on the Argentinians when it bombarded defensive positions around Port Stanley. Then the vessel became the first British warship to be attacked in the war when she was straffed by an Argentinian fighter aircraft that fortunately lacked any ground attack weapons. When the Type 42 destroyer HMS Sheffield was hit by an Exocet missile on May 4th it was Arrow that lead the rescue effort taking off 225 of her crew. The ship would also undertake firefighting efforts for HMS Plymouth later in the war.

On the 10th May 1982, HMS Arrow continued to distinguish herself in combat when along with her sister ship HMS Alacrity she took part in a dramatic chapter of the war when both entered Falkland Sound under the cover of darkness to establish whether the Argentinians had mined the area. Just how they were supposed to detect the mines remains a topic of intense debate with the most cynical arguing that the Royal Navy viewed these ships as expendable compared to a Type 22 or Type 42 destroyer and so if they hit one it wouldn’t be such a loss in the grand scheme of things. The ships passed through the sound without encountering any mines but in the early hours of the following morning the frigates encountered the Argentine supply vessel ARA Isla de los Estados attempting to run supplies to the Argentine garrison. The rules of engagement permitted the frigates to attack and HMS Alacrity fired fifteen 4.5inch rounds from her DP gun which ignited the huge amounts of fuel and ammunition onboard. The resulting explosion destroyed the vessel killing 22 of the 24 crew in the only surface-to-surface combat of the war. That wouldn’t be the end of it however. As the two vessels completed their mission and turned back towards the taskforce they were spotted by the Argentine submarine ARA San Luis. The submarine fired on the two ships but both torpedoes failed to find their targets as a result of successful countermeasures employed by Arrow. Mechanical problems prevented the San Luis from attacking again and the submarine slipped away.

With the Argentine Navy’s surface force taken out of the fight by the sinking of the ARA Belgrano the main threat now came from low level fast jets of the Argentine air forces. The Sea Cat SAM proved almost impotent in defending against this type of attack and the 20mm Oerlikons proved a more effective anti-aircraft weapon prompting the fitting of an additional pair further aft later in the ships’ careers. It was because of this impotency against fast jets that two of the class were the major Royal Navy casualties in the war and both would be lost within two days of each other during the vital San Carlos landings. For the better part of a week the Royal Navy fought one of the most pitched and deadly battles in its history as the Royal Navy desperately tried to fend off the Argentinian air force who were trying to stop the British from putting troops and supplies on the island.

Sea Cat

Sea Cat

HMS Ardent was hit first on the 22nd May by two bombs from an Argentine aircraft both of which landed on the flight deck. The vessel remained afloat as firefighting efforts, including support from HMS Yarmouth (below), tried to save the vessel but later in the day the ship was hit again in another air attack by Argentine pilots who saw it as a target of opportunity. From a tactical perspective this was a mistake by the Argentine pilots since Ardent was already out of the fight due to the damage sustained in the first attack and was certainly out of the war. Therefore by attacking Ardent they were risking their lives for a tactically insignificant target, throwing away their bombs that would have better served being used against one of the other RN ships that hadn’t been hit yet.

TYPE 21 5a

On May 23rd 1982, HMS Antelope was hit during an air strike on the British ships at San Carlos. The attacking Argentine pilot flew his aircraft so low that as he passed over Antelope his wing struck the radar mast although he was able to maintain control and return to Argentina. One of his stick of bombs broke through the hull of the ship killing steward Mark Steven however its arming pin had failed to engage. A follow up attack saw a second bomb strike the ship but again the weapon failed to detonate. The ship was moved to more sheltered waters as a bomb disposal team worked through the night to disarm it.

After three attempts to disarm one of the weapons the team used a small explosive charge to try and destroy it in a controlled explosion. Unfortunately, this detonated the weapon and in the early hours of May 24th the night was illuminated by an immense explosion as the ship’s hull was torn open. A newspaper journalist nearby photographed the blast and the picture has become one of most enduring images of the war.


HMS Antelope

One of the cold realities of war regarding both these losses is that it was better that they got hit by the Argentine bombs rather than the troopships they were protecting during the landings. The troopships were crammed full of soldiers and several of them were requisitioned ocean liners that had no armoured protection or adequate countermeasures to tackle combat damage. In this respect their sacrifice meant they achieved their mission which in the Nelsonian traditions of the Royal Navy is an honourable fate for any ship.

While the remaining five ships survived the war they did not come off entirely unscathed. Their prolonged use in the South Atlantic during a bitter winter conflict had weakened their hulls requiring significant strengthening efforts to prolong their useful lives in the mid 1980s. This strengthening increased the displacement of the ships by a few hundred tons depending on the extent needed. The tragedy of the type in the Falklands campaign spelled the end for this class in the Royal Navy however and when an offer was made from Pakistan in the mid 1990s to buy all six remaining ships it was greeted with open arms. In a final irony the class that had failed to win any export orders was now being sold abroad second hand.

The class could be described as a failure in Royal Navy service and if this is true then the blame has to be put on both the naval architects and the Royal Navy both of whom were unable to meet in the middle with what they wanted. With no Royal Navy specification the shipyards produced a ship with no clear approach to its surface combat role. When it did go to war it was then put in to a situation for which it was totally unsuited, to provide air defence for the landings at San Carlos against fast jet types, and the class suffered accordingly. The Sea Cat installation was always considered a mistake and should have been replaced ideally by the superlative Sea Wolf SAM which would have gone a long way to saving Ardent and Antelope and perhaps then the retrospective view of this class might not be so tainted. That having been said the success of HMS Arrow in the conflict shows that not for the first time in its history it was the most important weapon system in the Royal Navy’s arsenal, its skilled and professional people, that made that particular ship a success.

Role: General Purpose Frigate

Displacement: 3,100tons (standard) / 3,700tons (full load) – both figures increased following strengthening.

Complement: 175 Officers and Crew


  • Length: 384ft
  • Beam: 41.7ft
  • Draught: 19.5ft


  • Primary: 2x Rolls-Royce Olympus gas turbines (50,000shp)
  • Secondary: 2x Rolls-Royce Tyne gas turbines (9,900shp)
  • Max Speed: 30kts
  • Max Range: 4,000nm at 17kts


  • 1x 4.5inch DP gun
  • 4x MM38 Exocet SSM
  • 1x Sea Cat SAM
  • 2x 20mm Oerlikon AA guns (Additional pair added post 1982)
  • 2x Triple cell Mark 44/46 ASW torpedo mounts

15 responses to “Type 21 Frigate

  1. Thoroughly interesting read, well done!
    Once in the Red Sea aboard a frigate armed with Sea Cat I did get to witness how good these weapons were……on a bad day!

    It was during an Admirals Inspection and three propeller driven very small target drones had been uploaded for Sea Cat trial shoots. It was a calm day with the sea like glass, no wind, conditions perfect in other words. The first drone was set up then launched from the frigates helicopter flight deck, thirty yards tops and ‘SPLAT’ it flopped into the sea! Down went the sea boat and picked up the floating target drone and back to the ship. Second drone set up and launched, this one got about forty yards and then ‘SPLAT’ and into the sea it did go. Down the sea boat and brought that one back. Third and last drone set up and launched and this one staggered into the air, cheers were heard!
    Sea cat then launched, and hit the sea about thirty yards from the ship, now ironic cheers heard. And that was that, no more sea cat launches that day.

    Liked by 1 person

  2. Pingback: 34 Years Ago Today – HMS Ardent Is Hit | Defence of the Realm

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  4. With regards to your commentary on HMS Antelope, you mention that after the two unexploded bombs entered her, that the ship was moved to sheltered waters and largely abandoned so that the bomb disposal team could defuse the two bombs. I’m afraid that this is inaccurate. Our entire crew remained on board throughout and many of us were on the flight deck or in the hanger when the bomb in the engine room detonated. You also mention that the SeaCat misfile was controlled by a control column – this was its secondary mode of operation. It’s primary mode was via a radar director and a camera tracking a flare on the back of the misfile. The radar would be locked onto the target and the camera (also mounted on the director), would send radio commands to guide the missile to the center of the radar image (the target). The pedestal (what you referred to as a control column), was the secondary mode of control.

    Liked by 1 person

  5. Neither the Tyne gas turbine nor its’ COGOG playmate the Olympus provided the ship’s electrical supply. This was provided by 4 diesel generators. The gas turbines were for propulsion only as with the Type 22 frigate & Type 42 destroyer. As you say, a fine looking ship for peacetime duties but sadly didn’t perform too well otherwise?
    Many thanks.


  6. Wasnt this class of ships not designed by the MoD naval constructors, which was a first for a long time. The lead designers ( with RCNC oversight in some areas, like ship stability) were Vosper Thorneycroft and Yarrow who were the yards that built them. Cracks in the upper structure were to plague many warship designs, some say it was due to the CAD approach, even to to more recent US Burke class


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